diff --git a/app/jobs/application_job.rb b/app/jobs/application_job.rb
deleted file mode 100644
index 97fc265f..00000000
--- a/app/jobs/application_job.rb
+++ /dev/null
@@ -1,5 +0,0 @@
-# frozen_string_literal: true
-
-class ApplicationJob < ActiveJob::Base
-  queue_as :default
-end
diff --git a/app/jobs/runner_cleanup_job.rb b/app/jobs/runner_cleanup_job.rb
deleted file mode 100644
index f578e9d5..00000000
--- a/app/jobs/runner_cleanup_job.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-# frozen_string_literal: true
-
-class RunnerCleanupJob < ApplicationJob
-  CLEANUP_INTERVAL = CodeOcean::Config.new(:code_ocean).read[:runner_management][:cleanup_interval].seconds
-
-  after_perform do |_job|
-    # re-schedule job
-    self.class.set(wait: CLEANUP_INTERVAL).perform_later
-  end
-
-  def perform
-    Rails.logger.debug(Time.zone.now)
-    Runner.inactive_runners.each do |runner|
-      Rails.logger.debug("Destroying runner #{runner.runner_id}, unused since #{runner.last_used}")
-      runner.destroy
-    end
-  end
-end
diff --git a/app/models/runner.rb b/app/models/runner.rb
index 653bc886..cb566661 100644
--- a/app/models/runner.rb
+++ b/app/models/runner.rb
@@ -15,14 +15,10 @@ class Runner < ApplicationRecord
 
   validates :execution_environment, presence: true
   validates :user, presence: true
-  validates :time_limit, presence: true
-
-  scope :inactive_runners, -> { where('last_used < ?', Time.zone.now - UNUSED_EXPIRATION_TIME) }
 
   def self.for(user, exercise)
     execution_environment = ExecutionEnvironment.find(exercise.execution_environment_id)
-    runner = Runner.find_or_create_by(user: user, execution_environment: execution_environment,
-                                      time_limit: execution_environment.permitted_execution_time)
+    runner = Runner.find_or_create_by(user: user, execution_environment: execution_environment)
 
     return runner if runner.save
 
@@ -41,7 +37,6 @@ class Runner < ApplicationRecord
   end
 
   def execute_command(command)
-    used_now
     url = "#{runner_url}/execute"
     response = Faraday.post(url, {command: command}.to_json, HEADERS)
     if response.status == 404
@@ -75,6 +70,7 @@ class Runner < ApplicationRecord
 
   def new_runner
     url = "#{BASE_URL}/runners"
+    time_limit = CodeOcean::Config.new(:code_ocean)[:runner_management][:unused_runner_expiration_time]
     body = {executionEnvironmentId: execution_environment.id, timeLimit: time_limit}
     response = Faraday.post(url, body.to_json, HEADERS)
     response_body = parse response
@@ -89,9 +85,4 @@ class Runner < ApplicationRecord
   def parse(response)
     JSON.parse(response.body).deep_symbolize_keys
   end
-
-  def used_now
-    self.last_used = Time.zone.now
-    save
-  end
 end
diff --git a/config/initializers/jobs.rb b/config/initializers/jobs.rb
deleted file mode 100644
index f4bf7be2..00000000
--- a/config/initializers/jobs.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-# frozen_string_literal: true
-
-RunnerCleanupJob.perform_now unless Rake.application.top_level_tasks.to_s.match?(/db:|assets:/)
diff --git a/db/migrate/20210415064948_create_runners.rb b/db/migrate/20210519134938_create_runners.rb
similarity index 67%
rename from db/migrate/20210415064948_create_runners.rb
rename to db/migrate/20210519134938_create_runners.rb
index 3ebebb63..e747ed4a 100644
--- a/db/migrate/20210415064948_create_runners.rb
+++ b/db/migrate/20210519134938_create_runners.rb
@@ -1,12 +1,10 @@
-class CreateRunners < ActiveRecord::Migration[5.2]
+class CreateRunners < ActiveRecord::Migration[6.1]
   def change
     create_table :runners do |t|
       t.string :runner_id
       t.references :execution_environment
       t.references :user, polymorphic: true
-      t.integer :time_limit
       t.float :waiting_time
-      t.datetime :last_used
 
       t.timestamps
     end
diff --git a/db/schema.rb b/db/schema.rb
index b899981c..fb4dbc1d 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2021_05_12_133612) do
+ActiveRecord::Schema.define(version: 2021_05_19_134938) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_trgm"
@@ -344,13 +344,11 @@ ActiveRecord::Schema.define(version: 2021_05_12_133612) do
     t.bigint "execution_environment_id"
     t.string "user_type"
     t.bigint "user_id"
-    t.integer "time_limit"
     t.float "waiting_time"
-    t.datetime "last_used"
-    t.datetime "created_at", null: false
-    t.datetime "updated_at", null: false
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
     t.index ["execution_environment_id"], name: "index_runners_on_execution_environment_id"
-    t.index ["user_type", "user_id"], name: "index_runners_on_user_type_and_user_id"
+    t.index ["user_type", "user_id"], name: "index_runners_on_user"
   end
 
   create_table "searches", id: :serial, force: :cascade do |t|