“I ended up spending the night in a cheap hotel.”

You're telling a story about a silly mistake you made when you left your keys at work and couldn't get into your apartment. You've described what happened, and now you want to explain the result of this event. You say:

I ended up spending the night in a cheap hotel.

(someone) ended up (doing something)

When you're telling a story about something that happened, sometimes you don't want to tell everything that a person did. You just want to tell what happened last. To express this, you say that someone "ended up ___ing". For example:

We had a great time sitting around talking, and we ended up going to bed at about four in the morning.

Jason looked for a job for about 6 months, and he finally ended up taking a job waiting tables at a sushi restaurant downtown.

spend the night (somewhere)

To "spend the night" somewhere means to sleep somewhere other than your own home. You can "spend the night":

• at your friend's house
• at a hotel
• with your girlfriend or boyfriend

a cheap hotel

"A cheap hotel" is one that doesn't cost much and is not very nice.