In short: A subscription is a contract for a service you pay for regularly — every month or every year — until you cancel it; it often renews automatically.
Simply put: Small recurring costs look trivial but add up to a large sum over a year. Subscription businesses also profit from us forgetting what we pay for. In the contract look for four things: the monthly cost, how long you are tied in, whether it renews by itself and what cancelling costs. Put every subscription in your budget with its renewal date.
Example: Four subscriptions at €9.99, €12.99, €5.99 and €14.99 add up to €43.96 a month — €527.52 a year.
Watch out: For a service contract concluded online or by phone, the 14-day withdrawal period in the EU runs from the day the contract is concluded — not from the first payment.
Source: Directive 2011/83/EU on consumer rights, art. 9 — https://eur-lex.europa.eu/eli/dir/2011/83/oj